Abstract: With the development of digital welding inverter and soft switching welding inverter,it is vital to develop digital PWM chip to meet the demand of digital control system.Base on the study and analysis of the principle about PWM chip,the digital PWM chip is established in VHDL within Altera's integrated development environment.The result of computer simulation and power load experiment verify that the PWM chip can meet the requirement of fast signal transmission on DSP and driving IGBT on welding inverter.Besides its flexible design and high reliability,the system has good anti-interference performance.